Sepsis is a prevalent and life-threatening medical condition characterized by development of a dysregulated inflammatory immune response and associated tissue damage. This dysregulated inflammatory response is initiated by activation of Toll-Like receptor (TLR) signaling in response to bacteria and/or bacterial products, such as LPS. Current treatments are limited and involve the use of antibiotics to control infection and supportive measures to assist patients with multi-organ failure. New treatment strategies are needed to address the dysregulated immune response seen in patients with sepsis, thereby limiting tissue damage and enhancing survival rates. We have identified and characterized a novel peptide, termed P13, a potent yet temporary inhibitor of intracellular TLR signaling. Studies performed under the current Phase II SBIR grant have i) demonstrated that P13 is a potent inhibitor of in vivo serum inflammatory mediators in animals administered both low-dose and high-dose LPS, ii) established the efficacy of P13 to significantly enhance survival rates in a lethal high-dose LPS-induced model of sepsis, iii) established the efficacy of P13 to enhance survival rates in the clinically relevant cecal ligation and puncture (CLP) polymicrobial sepsis model, and iv) demonstrated in pilot experiments a favorable safety profile for P13. P13, when administered after initiation of systemic inflammation and disease, improved the survival rate in these models 30-50% as compared with 0% survival in control treated animals. The primary goal of this Phase II Renewal Application is to complete all pre-clinical efficacy and safety testing required by the FDA for approval of this peptide as a new therapeutic in human clinical trials. Based on our studies showing efficacy of P13 to improve survival rates in sepsis pre- clinical models and data demonstrating a favorable safety profile, we propose in this Phase II Renewal Application to conduct all necessary studies required by the FDA to position P13 for human clinical trials. These studies will include establishing optimal P13 treatment parameters in the CLP model and development of a sensitive assay for detection of P13 in serum and tissues (specific aim #1). These studies will support appropriate P13 dosing and exposure parameters for the IND-enabling studies required by the FDA for drug approval. In support of the IND filing to the FDA for drug approval of P13, an optimal clinical treatment protocol and identification of biologic markers associated with P13 treatment will be determined (specific aim #2). Detailed IND-enabling studies for P13, providing a complete non-clinical pharmacology, pharmacokinetic, and toxicology data package will be performed (specific aim #3). At the conclusion of this Phase II Renewal Application an IND will be filed with the FDA for use of P13 in a Phase I human clinical trial.